AWS SDK GetSpotPlacementScores是在AWS EC2中获取Spot实例部署得分的API。但是使用该API时会存在rate limiting的问题，即出现请求次数受限的情况。

解决该问题的方法是在请求GetSpotPlacementScores之前获取一个AWS Security Token Service (STS)的token，然后将token添加到SDK配置的默认凭证提供程序中。这样就可以使用该API而不会受到rate limiting的限制了。下面是一个Python SDK的示例代码：

import boto3
from botocore.credentials import RefreshableCredentials
from botocore.session import Session

session = Session()
sts_client = boto3.client('sts')

def get_session_token():
    token = sts_client.get_session_token()
    return (token['Credentials']['AccessKeyId'],
            token['Credentials']['SecretAccessKey'],
            token['Credentials']['SessionToken'],
            token['Credentials']['Expiration'])

def refresh_credentials():
    access_key, secret_key, token, expiration = get_session_token()
    return RefreshableCredentials.create_from_metadata(
        metadata={
            'access_key': access_key,
            'secret_key': secret_key,
            'token': token,
            'expiry_time': expiration
        },
        refresh_using=get_session_token,
        method='sts-assume-role'
    )

# 将凭证提供程序添加到SDK配置中
session_credentials = refresh_credentials()
boto3.setup_default_session(credentials=session_credentials)

# 使用GetSpotPlacementScores API进行调用，并处理返回结果
ec2_client = boto3.client('ec2')
response = ec2_client.get_spot_placement_scores(
    DryRun=False,
    SpotInstanceRequests=[
        {
            'SpotInstanceType': 'one-time',
            'LaunchedAvailabilityZone': 'us-west-2',
            'SpotPrice': '0.03',
            'InstanceCount': 1,
            'ProductDescription': 'Linux/UNIX (Amazon VPC)'
        },
    ]
)
print(response)